feat: Add docker reproducible builds (#6799)

Which issue # does this PR address?

This PR addresses reproducible builds. The current dockerfile builds the lighthouse binary but not reproducibly.
You can verify that by following these steps:
```
docker build --no-cache --output=. .
mv usr/local/bin/lighthouse lighthouse1
rm usr/local/bin/lighthouse
docker build --no-cache --output=. .
mv usr/local/bin/lighthouse lighthouse2
sha256sum lighthouse1 lighthouse2
```
You will notice that each one of the binaries has a different checksum upon each build. This is critical for systems that depends on requiring reproducible builds, such as running lighthouse in confidential computing, like Intel TDX.


  This PR adds a new build profile as well as a Dockerfile.reproducible that enables building the lighthouse binary reproducibly.
By following the steps I listed above, you will be able to verify that the resulted binary has the same hash upon several subsequent builds for the same version.

How to test it:
```
mkdir output1 output2
docker build --no-cache -f Dockerfile.reproducible --output=output1 .
docker build --no-cache -f Dockerfile.reproducible --output=output2 .
sha256sum output1/lighthouse output2/lighthouse
# hashes should be identical
rm -rf output1 output2
```

Dockerfile.reproducible

@@ -0,0 +1,44 @@
+# Define the Rust image as an argument with a default to x86_64 Rust 1.82 image based on Debian Bullseye
+ARG RUST_IMAGE="rust:1.82-bullseye@sha256:ac7fe7b0c9429313c0fe87d3a8993998d1fe2be9e3e91b5e2ec05d3a09d87128"
+FROM ${RUST_IMAGE} AS builder
+
+# Install specific version of the build dependencies
+RUN apt-get update && apt-get install -y libclang-dev=1:11.0-51+nmu5 cmake=3.18.4-2+deb11u1
+
+# Add target architecture argument with default value
+ARG RUST_TARGET="x86_64-unknown-linux-gnu"
+
+# Copy the project to the container
+COPY . /app
+WORKDIR /app
+
+# Get the latest commit timestamp and set SOURCE_DATE_EPOCH (default it to 0 if not passed)
+ARG SOURCE_DATE=0
+
+# Set environment variables for reproducibility
+ARG RUSTFLAGS="-C link-arg=-Wl,--build-id=none -C metadata='' --remap-path-prefix $(pwd)=."
+ENV SOURCE_DATE_EPOCH=$SOURCE_DATE \
+    CARGO_INCREMENTAL=0 \
+    LC_ALL=C \
+    TZ=UTC \
+    RUSTFLAGS="${RUSTFLAGS}"
+
+# Set the default features if not provided
+ARG FEATURES="gnosis,slasher-lmdb,slasher-mdbx,slasher-redb,jemalloc"
+
+# Set the default profile if not provided
+ARG PROFILE="reproducible"
+
+# Build the project with the reproducible settings
+RUN cargo build --bin lighthouse \
+    --features "${FEATURES}" \
+    --profile "${PROFILE}" \
+    --locked \
+    --target "${RUST_TARGET}"
+
+RUN mv /app/target/${RUST_TARGET}/${PROFILE}/lighthouse /lighthouse
+
+# Create a minimal final image with just the binary
+FROM gcr.io/distroless/cc-debian12:nonroot-6755e21ccd99ddead6edc8106ba03888cbeed41a
+COPY --from=builder /lighthouse /lighthouse
+ENTRYPOINT [ "/lighthouse" ]